Audi's FSI direct fuel injection system is an engineering marvel. Winning the 24 Hours of Le Mans on its debut by providing increases in both power and fuel efficiency, consumers have been able to purchase vehicles equipped with it since late 2005.
The idea of direct injection is that you inject gasoline directly into the combustion chamber of your engine, which requires extremely high fuel pressures to counteract cylinder pressures and properly atomize fuel--on the order of 100-130bar, or 1500-1900psi. The FSI system uses a high pressure fuel pump to build up to these pressures. This pump consists of a piston and electronic pressure regulator, and is driven off of a special lobe on the intake camshaft. Because of this relationship, the volume of fuel delivered to the fuel injectors is dependant on engine RPM. The stock turbo, when paired with a full exhaust, intake, and intercooler, is capable of exceeding the fuel supply available from the stock fuel pump from 3000-5000rpm (as shown on the attached chart). In order to go to a K04 turbo or something larger, a solution is needed.
In order to address the lack of fuel in the midrange, the APR FSI fuel pump increases the volume of fuel from the high pressure pump by over 40%. Simplified, this is achieved by modifying some key internal parts within the pump. Changing these components requires precision machining of the new components with special surface treatments as well as enlarged, redesigned seals. Using inferior components on this critical part can lead to many problems from gasoline in the engine oil (from a bad seal) to complete engine failure (from a seized piston in the high pressure pump).
To give an idea of the tolerances involved, the final surface finish on the piston inside the fuel pump is so critical that it can be damaged by touching them with bare hands. The tolerances between the piston and the new barrel the piston rides in can only be measured by a multi-million dollar machine which uses air volumes to measure the part clearances to within microscopic levels.
The components used in the APR pump are also of a high caliber. The piston and barrel of the new pump are made of a certified and heat-treated bearing-grade stainless steel and have a special diamond like coating. The seals used in the pump are made of a high performance, filled polymer with a high modulus spring to retain the seal forces throughout the life of the product. The cross section of the seal is also of a proprietary design to maintain integrity over many years of use.
To ensure flawless drivability the APR 2.0T FSI fuel pump requires APR engine management recalibration to allow for the increased size of the APR fuel pump. If you already have APR software installed this recalibration upgrade is free, otherwise it needs to be purchased separately. Currently, some APR Stage II clients will be able to take advantage of increased horsepower and torque up to 25hp and 35lb ft with APR fuel pump specific engine management performance recalibrations.
Your ECU will need to be sent in to us for the software to be installed. Complete and include this form with your ECU, omitting the payment section at the bottom. Local customers may stop in to our Fremont, CA facility to have the upgrade performed, contact us for information on arranging this.
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This product was added to our catalog on Tuesday 29 March, 2011.